Gas-filled tube circuits



Ja 25, 1938. L, K, WART 4 2,106,286

GAS-FILLED TUBE CIRCUITS Original Filed Nov. 5, 1935 INVENTOR LESll/tl/Y ATTORNEY Patented Jan. 25, 1938 UNIT STATES 2,106,286 GAS-FILLED TUBECIRCUITS Leland Kasson Swart, signer to American Company,

Mountain Lakes, N. 1..- Telephone and Telegraph a corporation of NewYork Application November 5, 1935, Serial No. 48,379 Renewed November30, 1937 11 Claims.

This invention relates to electrical circuits and systems. Moreparticularly, this invention relates to recording systems and isintended to be especially useful for recording electrical voltages. Theapparatus and circuits of this invention are applicable to record steepwave front voltages and will record direct voltages as well asalternating voltages of steep wave front.

This invention also relates to gas-filled tubes and to circuits forgas-filled tubes. More particularly, this invention relates toarrangements for measuring voltages or currents and obtainingmeasurements from low voltages applied to the measuring apparatusthrough cold cathode gas-filled tubes.

Cold cathode gas-filled tubes generally require fairly high potentialsto ionize the gas between their electrodes. Such high potentials may beobtained through the use of input transformers or through biasingsources of potential or both. The use of input transformers in measuringcircuits is undesirable especially for measuring or recording steep wavefront impulses and transients, due to the change in the wave form thetransformer will produce for frequencies outside of its normal operatingrange, this change arising from the non-linear characteristics of thetransformer. If on the other hand biasing potentials are employed toreduce the initial operating voltage, which exceed the sustainingvoltage between the input electrodes of the tube, special means must beemployed to restore the gas to its deionized condition after withdrawalof the applied voltage. In accordance with this invention, the biasingpotentials exceed the sustaining voltage of the tube and the outputcircuit includes special circuits to restore the gas to its originaldeionized state. Moreover, even though the output circuit may includearrangements for deionizing the gas,,yet where the applied voltage atthe input exceeds the sustaining voltage, the invention further providesmeans for temporarily reducing :the voltage in the input circuit of thetube below the sustaining value. To accomplish this latter feature, aresistance or resistance and condenser may be inserted into the inputcircuit of the tube to produce a potential drop across its terminalsupon the passage of current therethrough for counteracting the effect ofthe biasing potential.

The invention will be better understood from the detailed descriptionhereinafter followin when read in connection with the accompanyingdrawing which shows two embodiments of the invention merely for thepurpose of illustration.

In Figure 1, an impedance Z1 is bridged across the input circuit. Theouter adjustable terminals are connected to the cathodes K1 and K2 ofgasfilled tubes N1 and N2 which may be of the hot or cold cathode type,the interconnecting circuit -5 including resistors Z2 and Z: which areemployed to limit the current applied to these cathodes. The source ofpotential B1 is connected between a point approximately midway betweenthe terminals of impedance Z1 and the cathodes K3 and K4 of the twotubes through a resistor Z4. The latter source of potential is greaterthan the sustaining voltage of the tubes but less than the voltagesrequired to start gaseous ionization within these tubes. Source B1 isemployed to bias the cathodes K1 and K2 with respect to thecorresponding electrodes K: and K4 and it reduces the voltage suppliedby the input circuit through impedance Z1 required to initiate gaseousionization within the tubes.

The anodes A1 and A: of tubes N1 and N2 respectively are connectedtogether and are part of a so-called work circuit which includes thewindings of relays R1 and R2, the battery or other source B2 and theimpedance Z4. The terminal common to the windings of relays R1 and R2 isconnected to the cathodes K3 and K4 through a resistor Z5 and acondenser C1.

The relay R1 is a vibrating relay and it operates to suppress thevoltage in the work circuit and hence to deionize the gas within bothtubes. This is described in more detail in my Patent 1,977,256 issuedOctober 16, 1934. The relay R2 acts as a work relay and it operatesrecording mechanism'relay R3, as will be subsequently described. Therelay R: has its winding in a circuit which includes the armature andcontact of relay R2 and the source 32. The current in the winding ofrelay R1 is controlled by the resistor Z6. The relay is neverthelessunder the control of relay R2. 40

The relay R3 is of a slow-acting type, its armature closing itsassociated contact slowly. As the armature and contact of relay R3 arein the resetting circuit of the tubes N1 and N2, the delay so introducedis for the purpose of providing ample time for the recording mechanism,of which relay Ra is a part, to operate properly. The resetting circuitjust referred to includes the armature and contact of relay R3, thearmature and contact of relay R1 and the parallel circuit which includesthe winding of the latter relay as one branch and the resistor Z5 andcondenser C1 as the other branch.

The arrangement of Fig. 1 operates as follows: The potential impressedacross impedance Z1 is divided into two parts which are applied throughresistors Z2 and Z: to the cathodes K1 and K3 and K1 and K; respectivelyof the tubes N1 and N2. The potential impressed upon one of these pairsof cathodes will be aided by the potential of source B1 and the otherpotential will be opposed by that of B1. If it be assumed that thepotential applied to impedance Z1 is an alternating potential and of asufllcient magnitude, then the gas within both tubes will becomealternately ionized by the incoming potential. Upon the ionization oftube N1, current will flow through the work circuit which includes,among other things, the windings of relays R1 and R2 and the anode A1and the cathode Ka of tube N1. Both of the relays R1 and R2 will operateand the operation of relay R2 will cause relay R3 to operate. Thearmature and contact of relay R3 complete a circuit as follows: Thearmature and contact of relay R3, the contact and armature of relay R1,the winding of relay R1, the anode A1 and the cathode & of the tube N1back to the armature of the relay R3. This circuit will withdrawpotential from the winding of relay R1 and hence reduce the potentialbetween the anode A1 and cathode K1 to a value less than that requiredto sustain the glow between these electrodes of the tube. At the sametime the current through the winding of relay R2 is increased becauseall of the potential B: is applied thereto. The latter current alsoflows through resistor Z1 and is in a direction'to oppose that producedby source B1 and applied to the cathodes K1 and Ka of tube N1. As theincreased biasing potential exceeds the sustaining voltage at the inputelectrodes of the tube, this counter voltage of course materiallyreduced the potential between the cathodes K1 and K3 below thesustaining voltage and, in the absence of additional voltage at theinput circuit, 5.. e. applied from the input circuit across the upperhalf of impedance Z1, the glow between electrodes K1 and K3 will beextinguished. Upon deionization of the gas within tube N1, potentialbecomes removed from the winding of relay R1, the armature of the latterrelay will leave its contact and the potentials of sources B1 and B2will be restored to the anode A1 and cathode K: and K1 of tube N1. If,however, potential is still applied across within tube will reoperate.

Thus, relay R1 vibrates continuously while voltage is applied from theinput circuit and holds relay R2 continuously operated which in turnholds relay R3 continuously operated. However, when the armature ofrelay R1, leaves its contact and on disappearance of the voltage appliedby the input circuit, the tube N1 becomes deionized and remainsdeionized and relays R2 and R3 restore to normal.

The same sequence of events occurs when the potential applied by theinput circuit is reversed in polarity except that the electrodes of tubeN: are brought into the operating circuits.

The resistor Z5 and absorb the voltage set up by the winding of relay R2when the armature of relay R1 leaves its contact. Absorption of thisvoltage is required in order to prevent reionization of the gas withineither tube on account of the addition of the voltage drop producedacross the winding of relay R: to that of source B2.

In Fig. 2 the relay R1 includes an additional armature at the left. Thisarmature is connected to the center top of impedance Z1. The contactcondenser C1 function to.

of this additional armature is connected to the negative terminal ofsource B1. A resistor Z1 is inserted between the positive terminal ofsource B1 and the center top of impedance Z1.

Upon the operation of relay R1, the closure of the right hand contact ofthe relay will complete a circuit, such as already described withrespect to Fig. 1, to deionize the gas between the electrodes A1 and &of tube N1 or between the electrodes A2 and K4 of tube N2, theseelectrodes being in the work circuit. Upon the closure of the left handcontact of relay R1, the potential applied between the two cathodes ofeach tube will, in the absence of additional voltage across impedanceZ1, be reduced practically to zero and the gas be tween these cathodeswill become deionized. The resistor Za and condenser C: may be connectedacross the left hand armature and contact of relay R1, as shown, inorder to prolong the time in which the voltage across both pairs ofcathodes is maintained below the sustaining voltage to insure completegaseous deionization between these cathodes.

Although this invention has been shown and described in certainparticular arrangements merely for the purpose of illustration, it willbe understood that the general principles of this invention may beapplied to other and widely varied organizations without departing fromthe spirit of the appended claims.

What is claimed is:

1. The combination of a gas discharge tube having input and outputcircuits connected to its electrodes, the electrodes of the tube forminga plurality of discharge paths one of which extends to the input circuitand another to the output circuit, means including sources 01' voltageconnected respectively in the input and output circuits for ionizing thegas between all of the discharge paths or the tube, and means responsiveto the discharge of the gas in the output circuit for simultaneouslyde-ionizing the gas within all of the discharge paths formed by theelectrodes to which both circuits are connected, said means beingconnected to the output circuit.

2. The combination of a gas-filled tube having three electrodes, aninput circuit connected to two of the tubes electrodes through whichvoltage may be applied to ionize the gas within the tube, an outputcircuit including a source of voltage connected between the thirdelectrode and one of the other electrodes of the tube, and meansresponsive to ionization of the gas within the tube for feeding voltagein the output circuit back to the input circuit to reduce the effectivevoltage of the input circuit below the value required to sustain gaseousionization within the tube.

3. The combination of a gas-filled tube having three normally coldelectrodes, an input circuit connected to two of the electrodes, anoutput circuit connected to the third electrode and one of the otherelectrodes, two sources of potential one of which is connected to theinput circuit and the other to the output circuit, and means connectedto the output circuit for periodically deionizing the gas between all ofthe electrodes of said tube.

4. The combination of a gas-filled discharge tube having at least threeelectrodes to which input and output circuits are connected, individual'sources of potential in said input and output circuits, and meansresponsive to the energization of the output circuit for continuouslyand periodically reducing the effective voltage of both of said sourcesof potential.

5. The combination of a three-electrode gasfilled tube, a source ofpotential, an impedance connected in series with said source between twoof the tubes electrodes, a second source of potential, a work circuitincluding said impedance and said second source oi potential andconnected between the third electrode and one of the other electrodes,means for continuously transmitting pulsating current through said workcircuit, and means for periodically deionizing the gas between all ofthe electrodes of the tube, said means being connected to said workcircuit.

6. The combination of a gas-filled tube havin electrodes, at source ofpotential for biasing one of the electrodes with respect to anotherelectrode to a potential exceeding the sustainin voltage between saidelectrodes, a second source of potential, a load circuit connected tothe third electrode and one of the other electrodes and including saidsecond source of potential, said load circuit including means forperiodically deionizing the gas between the electrodes to,

which said load circuit is connected and for simultaneously neutralizingthe voltage oi said source.

7. The combination a three-electrode gasillled tube, voltage biasingmeans connected between two of the electrodes and of a value exceedingthe sustaining voltage therebetween, a source of potential, a workcircuit connected between the third electrode and one of the otherelectrodes and including said source of potential, and means forperiodically deionizing the gas between the two electrodes'to which thework circuit is connected, said means including means connected to saidwork circuit for periodically deionizing the gas between the first twoelectrodes.

8. Voltage recording apparatus comprising a three-electrode gas-tilledtube, an impedance to which incoming voltages are applied, a source ofpotential connected to said impedance and to two of the tubeselectrodes, a vibrating relay, a load device, a recording relay, asecond source of potential supplying current through the winding of thevibrating relay and the third electrode and one of the other electrodesof the tube to said load device, means responsive to flow of current tosaid load device to operate the recording relay, and means connected tothe armature and contact of said vibrating relay to periodically nullity'the effect. of both sources of potential.

9. The combination of a three-electrode gasfllled discharge tube, asource of potential exceeding the sustaining voltage value but below thebreakdown voltage value connected to two of the tubes electrodes, asimilar source con-.

nected to the third electrode and one of the other electrodes, meansresponsive to the ionizationoi the gas within .the tube to periodicallyreduce the eflective potential of both sources below the sustainingvoltage value, said means being connected to the aforementioned circuitextending to said third electrode and said other electrode.

. 10. The combination of a three-electrode gasfllled tube, input andoutput circuits each connected to two 01' the tubes electrodes one ofwhich is common to both circuits, two sources of potential connectedrespectively to said input and output circuits the magnitudes of whichexceed the sustaining voltage value between the electrodes to which eachcircuit is connected, and means responsive to the application ofadditional voltage to the input circuit to simultaneously, synchronouslyand periodically deionize the gas between the two pairs of electrodes,said means including means for feeding voltage from the output circuitto the input circuit to reduce the elective voltage of the inputcircuit.

11. In a circuit having a three-electrode gasiilled tube providing twodischarge gaps, two sources of potential one for each gap, the magnitudeoi each of said sources exceeding the voltage required to sustain glowin its corresponding gaps, and means for periodically extinguishing theglow oi each gap, said means including means tor returning potentialacross one gap to the circuit oi the other gap to reduce the eiiectivepotential across the latter gap.

LELAND KABSON SWART.

